Hello,
This wasn't the detail I was expecting..
Your installation is claiming about the following:
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Error establishing a database connection
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This either means that the username and password information in your wp-config.php file is incorrect or we can not contact the database server at localhost. This could mean your host’s database server is down.
1) Are you sure you have the correct username and password?
2) Are you sure that you have typed the correct hostname?
3) Are you sure that the database server is running?
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Was typed 'localhost', is just only thing I can assure is correct.
You need to assure you login is correct.
Try to access the PhpMyAdmin in your server, and check if you can login to it.
If you can't login, you must to create a correct login.
If you can login correclty, you must check the permissions of your file:
/home/USERNAME/public_html/wp-config.php
It must needed to set +rw (or 666) to your username, at this file.
Do it with FileManager, ou SSH login to your server, with the following command:
# chmod +rw USERNAME:USERNAME /home/USERNAME/public_html/wp-config.php
...and do not provide your login details publicly, unless you want to be hacked. change it immediately.
Regards,
Netino